Liquid mixer and settler



Feb. 13, 1940.

c. w. sTRATFoRD LIQUID MIXER AND SETTLER Filed Dec. 8, 1937 Patented Feb. 131,` 1940 UNITED .STATES .Parent oFF-ics l y 2,190,247`

l y i LIQUID MiXERjA'NDsET'ritER y vCharleskW. Stratford, KansasCity',llIo.,-assignor` to Standard OiliCompany of California, San Francisco, Caliii ,ai corporation of'Delavvare i Applikation December s, 1937, serialNtyivsafie aciaims. (ol. 19e-46) This invention relates to a method and apparatus for the continuous`miiringA of liquids and solids'so that they may `react chemically, after which they are 'separated for reuse or disposal; and

particularlyfreiers tothoseoperations wherein a finely-divided solid reactive `material is suspended in an aqueousA liquid reactive materialand contacted im'th an untreated liquid` of less density, such vas an foil, said reactive materials being subsequently continuously7 kseparated from the treated liquid for use with -additional untreated liquid. In the continuous treatment of partially "renedloils, for example, sou-r gasoline or kerosene i withlead sulde' and caustic, according tothe. G. L'. ROWSQY PatentsNS. 1,754,649 and 1,954,103

andv the "E.S. Brown et al. Patent No. 2,049,423,

the oil to be treated is first contacted with a cau'stic solution-in which is suspended finely-divided lead sulde. These are intimately mixed in the presencevof air to promote contact and chemical reaction with the undesired components of the sour gasoline'or kerosenev andare then allowed to remain relatively quiescent so that gravity separation of the heavier caustic and lead sulfide will 25 take place. The separated caustic and lead sulfide are preferably continuously withdrawnand maybe used to treat additional quantities of untreated oil entering the system.

Inasmuch as the finely-divided particles of lead 3U sulde are individually quite dense, `it would be expected that they would quickly separateout of the oil and also readily fall to the bottom of any caustic layer that would underliethe oil in the settling chamber. Ithas been found,l however, that the lead sulde particles, perhaps dueto a surface tension effect, do not settle, but accumulate in considerable quantities throughout the system, particularly vat or near the interface between the separated layers'of voil and caustic and 40 also at the bottom of the caustic. Consequently,

the usual procedure for withdrawal, nainely, removing the supposedly separatedv caustic and lead sulde from the quiescent body of the same at the lowest portion of the settler cr from aseparate container below the main chamber has not proved completely successful.

This invention, therefore,4 comprehends broadly a method and means forkeeping the lead sulfide particles in suspension throughout the separated caustic layer or at least preventing their accumulation at thetop or at the bottom of the latter by agitating the same so that lthose two reactive materials may be continuously withdrawn in a uniform'and active condition for re-use as by 5 mixing Withthe incoming oil to betreated. Ob-

visusiy; enelinvun isynot soumises itsuse andr-'ay be suited to'other processes and fenvironf ments.; where applicable.

, It is an'ob'ject of thisinvention to provide an i improvedfforni ofljsettling apparatus combined `5 with' -agitatingmeansforcertain of the separated components," the effect of said agitation' being substantiallyconfined to a' restricted portion of theapparatus `so as not to'interfere with the v preceding settling operation. i l0 Another ob'jectlis to'provide an improved treating system fora mixture of liquids and'afinelydivided solid material', .whereby allthesolid `maof=settler andmix'er'embodying this invention.

i vFigure?l is a `vertical sectional view on line II--II of the apparatus of-Figure lion a plane transverseto the'longitudinal axis. n

Figure 3 isasirnp'liied:flow` diagram ofthe arr-230 rangementof the equipment of Figures `l` and 2. i Referring" to thedrawin'g and particularly to' `Figure which yillustrates a simplified 'ow dia` gramV ofa system in which 'thexinvention may be employedthe'reference numeral IIlillustrates a 35 source of 'sour oil, suchas gasoline or kerosene, and il isa source of reagent,v such as strong causticy soda solution. Normally, there is a constant flow of'sour oil through line l2 to amixing de- `vice or contaotor generally represented by num-'i140 eral i3, which may be ofthe centrifugal type disclosed 'in my Patent No.`1,-736,018-and driven by a suitable 'primemo'ver such as--motor I4. From contactorlSfa mixture of previously formed Lreagents 4and-oil passes through line I 5into settler45 Vtt,.vliereingravityfseparation of the nowy treated i oii and the reagentstakes place.` The treated and `separated" oil passes cutof settler IS through line All to a suitable storage sucha-s tank I8 while the heavier separated reagents drop-into-a mixerfm Vll'below ,settler-1 I6, fromvwhich they are withrawn through line E'by circulating pump 2 I;

The reagent stream, in this example a suspension of'lead sulfide invstrong caustic vsoda `solution; ,leaves the pumptzi, and then divides, partk 55 going back to contactor I3 through line 22 to treat incoming sour oil, and part returning through line 23 to a system of jets or nozzles 24 in mixer I9 to agitate the reagent accumulating therein in order to maintain its components in a proper and active suspension. As the reagent, particularly the caustic, becomes exhausted or depleted by the treating process, added amounts of stronger solution may be admitted to the circulating stream through line 22 from reagent source II.

Referring now to Figures 1 and 2 of the drawing, which illustrate in greater detail theI construction of the settler I6 and mixer I9, it will be noted that these are preferably, but not necessarily horizontal cylindrical tanks,r joined by a narrow elongated passage for a purpose whichy will be described in greater detail below.

The contacted oil and reagent inlet I to settler I6 is preferably arranged to give uniform liquid distribution, as-would be obtained from a header 25 branching into a distributor pipe 26, the latter slotted along its upper side as at 21. Pipe 26 is positionedin the upper part of a directing hood 2S, 'which is open at the bottom, as shown in .Figure 2. At the top of settler I6 is a gathering pipe 29 along the top of which is a narrow slot or a s'uccessionvof slots 30 into which the oil overflows, passing from pipe 29 intoline I1, as previously explained. An air vent 3l is provided from hood 28 vandshell l5 and is tted with any l suitable valve means to remove 'excess air and beneath gaseous residues from the system. Such a structure is generally illustrated in my Patent No. 1,868,775.

It has been found that the finely-divided lead -sulde tends to deposit in settler i6 on any except sloping surfaces, so that guiding baiiies or slide plates 32 arepreferably provided, one on each side of the center of the bottom or mixer i6, and set at an angle of about 30, to direct the downwardly settling heavier liquid and the solid particles therein to. a row of holes or slots 33, extending substantially the entire length of the mixer. 4 c

Mixer I9, previously mentioned, is positioned settler I6 and substantially parallel thereto. A series of holes or slots 34 are provided along the top of mixer I9, and are maintained in communication with holes 33 in settler I6 by an elongated narrow passage formed by plates 35 which connect the mixer and settler as shownin Figures l and 2. An arrangement such as that just described serves effectively to pass the downwardly settling liquid and solid reagents uniformly and continuously from settler I6 into mixer I9 and yet is effective to prevent turbulence and agitation of the liquids in mixer I9 being transmitted into settler I6 to interfere with the substantially quiescent liquid body therein.

Mixer I9 is provided with agitating means of any desired type, in this example, a distributor pipe generally designated 36, in which are mounted a series of downwardly and sidewardly directed jets or vnozzles 24. Recirculated reagents, and

' usually some oil are withdrawn through outlet ure 2 and keep the liquid and iinely-divided solid reagents in a uniform and effective suspension. One result particularly desired and which is attained by the arrangement-just described, is the source II. become yused up in the process, but merely requires a` certain minimum caustic concentration prevention of accumulations of the finely-divided solids at the interface between the layer of oil and the heavier layer of reagent below the oil and at the bottom of the heavier reagent layer. It has been discovered that the maintenance of a homogeneous suspension prolongs the effectiveness of the reagents so that the caustic in particular may be used to lowerv concentrations than have been possible heretofore.

In operation, the mixer I9 is charged with reagent, such as finely-divided lead sulfide suspended in a 32 Baume caustic soda solution, of a quantity sufficient to treat charged sour oil for a period of days,v say 5 to '7, the reagent occupying only a part of the mixer, and the latter being of such volumetric capacity that the dilureagent -is being circulated through the mixer I9,

pump 2I,\contactor I3 andv settler I6. As soon as the settler IB becomes lled with treated oil,

the latter meanwhile separating from the heavier reagents, the final treatedoil may be withdrawn through the o-il gathering pipe 29 to storage I8.

After the caustic has become diluted by chemical reaction-.with the sour oil or weakened by the treatment to a point below the desirable treating efficiency, a quantity of it is drawn out of the system and replaced by concentrated, for

example, 32 Baume caustic from the reagent The lead sulfide apparently does not to remain effective so long as it is adequately dispersed as is described herein.

As stated above, the results desired are obtained by rst providing a chamber in which the i -treated oil and vreagents may be substantially quiescent, so that complete separation may occur, the oil being continuously drawn off at the topof the chamber and the reagents being directed through the narrow passage between the settler and mixer into the latter, wherein the oilreagent interface or what would be itsl equivalent in a quiescent settler preferably is maintained, and wherein thereagents and probably some oil are agitated as by the recirculation system of this example, to keep the reagents in a suspension that'will be continuously effective and available for reuse with incoming oil to be treated.

Although. a certain specific construction and mode of operation are described and illustrated, it is obvious that many modiiications and changes could be made without departing from the invention, and all such that are within the scope of the appended claims are embraced thereby.

I claim:

l. An' apparatus of they character described comprising an upper container and a lower container, means for introducing a mixture of liquids of different density, together with a nely-divided solid, into said upper container for gravity separation therein, means for withdrawing the less dense liquid from the upper part of said upper container, means for withdrawing the denser yliquid together with a solid material suspended therein from the lowest part of said uptate the same as indicated by the arrows in Figper container in a narrow stream extending across substantially the full width of said container and introducing them into said lower container, means for withdrawing said denser liquid and said solid 'from said lower container and..."

means for agitating the contents of said lower container.

2. An apparatus according to claim `1 in which liquid injectionand dispersion system for said lower container. v i

4. An apparatus according to claim 1, in which both of said containers are horizontally arranged and of generally cylindrical shape, and the means for passing the denser liquid and solid material from the upper to the lower container comprises means forming an -elongated narrow passage substantially the full length of oneof said containers, to segregate said denser liquid and solid from said lighter liquid.

5. An apparatus according to claim 1, in which both of said containers are horizontally arranged and of generally cylindrical shape, rand said upper container is provided with downwardly converging guide means for directing solid particles to the means' `for withdrawing the said particles comprising two cylindrical containers horizontal- 1y disposed one above the other, and with their? longitudinally axes substantially parallel, agitating means for liquid in the lower of said containers, `means forming a narrow' outlet along the lowest portion of said upper container for substantially the entire length thereof, means forming a narrow inlet along the highest portion of said upper container, and means connecting said Vessels andenclosing said outlet and inlet to form a narrow elongated passage, s'o arranged .and constructed that agitation of liquid in said` lower container is substantially confined thereto,

and` accumulation of solid materials along the bottom ofsaid prevented.

'7.y An'apparatus according "to claim 6 in which upper container is substantially the outlet and inlet means therein specified comshells` thereof and said connecting means corri--4 prises enclosing plates secured to said shells'.

CHARLES w. s'I'RATFoRD. 

